This application incorporates by reference Taiwanese application Ser. No. 89116814, Filed Aug. 18, 2000.
1. Field of the Invention
The invention relates in general to a scanning apparatus having two transmission systems, and more particularly to a scanning apparatus capable of shortening the time for the carriage to move back to the start.
2. Description of the Related Art
Along with the continuous advance and progress of technology, the integration and application of multi-media is now an overpowering trend. Multi-media generally mean data in various format such as word, image, and voice. Therefore, multi-media apparatus for capturing image or voice come with the tide of fashion. Among that, image-scanning apparatus is one of the common image capturing apparatuses.
Referring to FIG. 1, a conventional flatbed scanning apparatus is illustrated. The conventional flatbed scanning apparatus includes a scanning platform 102 and a cover 104. Furthermore, as shown in FIG.2, there are an image capturing apparatus and a transmission system for transmitting the image capturing apparatus in the scanning platform 102.
The transmission system 106 transmits the carriage 108 to move forward and backward along the transmission guide way 110. The transmission system 106 includes a motor 112. The motor 112 is in conjunction with a transmission gear-wheel 114 and the transmission gear-wheel 114 is in conjunction with a high gear-change rate transmission gear-wheel (or gear set) 116. The motor 112 transmits the transmission gear wheel 114, the high gear-change rate transmission gear wheel 116 and the carriage 108 so that the carriage 108 can move along the transmission guide way 110 back and forth to scan the document 103 on the scan platform 102.
As high resolution of scanning apparatuses is required, gear sets with high gear-change rate are frequently used to meet the requirement. However, the applying of a high gear-change rate gear set lengthens the backward time of the carriage 108. A conventional way to solve the problem is by using higher rotating speed motors. The problems followed are high cost, temperature rising and noise.
It is therefore an object of the invention to provide an improved and simplified scanning apparatus with high image quality, short carriage backward time and high scanning efficiency simply by using one-way clutches to control the carriage""s motion.
According to the object of the invention, a scanning apparatus having two transmission systems is provided. The scanning apparatus includes a motor, the first transmission gear-wheel and the second gear-wheel, a relatively high gear-change rate transmission gear-wheel and a relative low gear-change rate transmission gear-wheel, the first one-way clutch, the second one-way clutch and a carriage. The first transmission gear-wheel and the second transmission gear-wheel are transmitted by the motor. The relatively high gear-change rate transmission gear-wheel is in conjunction with the first transmission gear-wheel. The relatively low gear-change rate transmission gear-wheel is in conjunction with the second transmission gear-wheel. The first one-way clutch disposed inside the relatively high gear-change rate transmission gear-wheel to control the relatively high gear-change rate transmission gear-wheel to rotate in a first direction. The second one-way clutch disposed inside the relatively low gear-change rate transmission gear-wheel to control the relatively low gear-change rate transmission gear-wheel to rotate in a second direction. The carriage is transmitted by the relatively high gear-change rate transmission gear-wheel through the first transmission belt to move forward and also the carriage is transmitted by the relatively low gear-change rate transmission gear-wheel through the second transmission belt to move backward.